Don’t plant the tree too deep. “Planting too deep is the source of many tree problems,” Yiesla said. Make sure the hole you dig is no deeper than the depth of the soil in the root ball or the container. When you set the tree in the hole, check that the root flare — the place where the trunk widens out into the roots — sits at the level of the surrounding soil. You may need to remove some of the soil in the root ball or container to find the root flare, so you can check that it is not too low. If necessary, lift up the tree and add more soil underneath to raise it. “Be sure to tamp that soil down gently to provide a solid foundation and keep the tree from settling and sinking,” she said.